JP6319050B2 - Turbocharger - Google Patents

Description

  The present invention relates to a turbocharger that opens and closes a flow rate adjusting valve and a wastegate valve with one actuator.

(Conventional technology)
A flow rate adjusting valve for adjusting an opening degree of an exhaust gas introduction path for introducing exhaust gas to a turbine impeller, and a waste gate valve for adjusting an opening degree of a bypass path for bypassing the turbine impeller, the flow rate adjusting valve and the waste gate A turbocharger that controls supercharging pressure by adjusting the opening of a valve is known.

As a turbocharger of this type, a turbocharger that opens and closes a flow rate adjustment valve and a wastegate valve with one actuator is known for the purpose of improving mountability and reducing costs (for example, see Patent Document 1).
The turbocharger disclosed in Patent Document 1 drives a flow rate adjustment valve by an actuator, converts an output of the actuator by a link device, and drives a wastegate valve by an output of the link device. The waste gate valve is provided to open during the change of the opening of the adjustment valve.

(Problems of conventional technology)
Generally, an open / close valve that opens and closes a flow path has high flow rate change sensitivity immediately after opening, and the flow rate change sensitivity decreases as the opening degree increases.
For this reason, when the operating angle of the actuator is gradually increased, there is no change in the supercharging pressure while the opening of the flow adjustment valve is increasing, and there is no change in the supercharging pressure. When the wastegate valve starts to open, the supercharging pressure drops sharply.

  Specifically, as shown in FIG. 5B, the change characteristic of the supercharging pressure with respect to the operating angle of the actuator includes “a range in which the supercharging pressure does not change (supercharging pressure dead zone Z)” and “a supercharging pressure suddenly increases. There is an adjacent portion that changes to “a”, and the change characteristic has a clear step shape. Then, when the actuator is changed for the supercharging pressure control, the “clear staircase supercharging pressure characteristic” becomes a deteriorating factor of the supercharging pressure controllability, and drivability is lowered.

  Further, using an example of pressure feedback of the actuator, if there is a “supercharging pressure dead zone Z in which the supercharging pressure does not change” during the change of the actuator operating angle, the target supercharging pressure changes and the actual overpressure changes. When the supply pressure is converged to the target boost pressure, there is a problem that the fluctuation range of the actual boost pressure becomes large and the convergence time becomes long (see the broken line J3 in the upper time chart of FIG. 5A). }.

JP 2012-57546 A

  The present invention has been made in view of the above-mentioned problems, and improves the controllability of the supercharging pressure in a turbocharger that drives a supercharging pressure control flow rate adjusting valve and a wastegate valve with one actuator. With the goal.

In the turbocharger of the present invention, the detour start opening θα at which the wastegate valve starts to open is set to the adjustment valve minimum opening θ0 side from the saturation minimum opening θL0.
As a result, the above-described supercharging pressure dead zone Z can be eliminated within the change range of the actuator. For this reason, by changing the actuator, the supercharging pressure can be continuously changed, and the controllability of the supercharging pressure can be improved.

1 is a schematic view of an intake / exhaust system of an engine (Example 1). (Example 1) which is explanatory drawing of the drive mechanism of a flow regulating valve and a waste gate valve. (A) The graph which shows the relationship between the turbine expansion ratio when the flow rate adjustment valve is changed and the turbine corrected flow rate, (b) The graph which shows the change of the turbine corrected flow rate with respect to the opening degree change of the flow rate adjustment valve (Example 1) ). (A) It is a graph which shows the opening degree change of a flow regulating valve and a wastegate valve with respect to the change of an actuator operating angle, (b) It is a graph which shows the supercharging pressure change with respect to the change of an actuator operating angle (Example 1). (A) A time chart showing an example of control by pressure feedback, (b) a graph showing a change in supercharging pressure with respect to a change in actuator operating angle (Example 1, Example 2, comparative example of conventional example). (A) A graph showing changes in the opening of the flow rate adjusting valve and the wastegate valve with respect to changes in the actuator operating angle, (b) a graph showing changes in supercharging pressure with respect to changes in the actuator operating angle, and (c) with respect to changes in the actuator operating angle. It is a graph which shows the relationship of the absolute value of a supercharging pressure sensitivity (Example 2).

  EMBODIMENT OF THE INVENTION Below, the form for inventing is demonstrated in detail based on drawing.

  A specific example of a turbocharger to which the present invention is applied will be described. In addition, the Example disclosed below discloses an example and it cannot be overemphasized that this invention is not limited to an Example.

[Example 1]
A first embodiment will be described with reference to FIGS.
An engine 1 for driving a vehicle (an internal combustion engine that generates rotational power by burning fuel, regardless of the type of fuel, regardless of the engine type such as a reciprocating engine or a rotary engine) is equipped with a turbocharger 2.

The engine 1 includes an intake passage 3 that guides intake air into the engine cylinder, and an exhaust passage 4 that purifies exhaust gas generated in the cylinder and discharges the exhaust gas into the atmosphere.
The turbocharger 2 is a supercharger that pressurizes the intake air sucked into the engine 1 by the energy of the exhaust gas discharged from the engine 1. The turbocharger 2 is driven by the exhaust gas of the engine 1, and the exhaust turbine 5. And an intake air compressor 6 that pressurizes the intake air sucked into the engine 1.

The exhaust turbine 5 includes a turbine impeller 5a that is rotationally driven by exhaust gas discharged from the engine 1, and a spiral turbine housing 5b that accommodates the turbine impeller 5a. Details of the exhaust turbine 5 will be described later.
The intake compressor 6 includes a compressor impeller 6a that is driven by the rotational force of the turbine impeller 5a to pressurize the intake air in the intake passage 3, and a spiral compressor housing that accommodates the compressor impeller 6a. The
The turbine impeller 5a and the compressor impeller 6a are coupled via a shaft 7, and the shaft 7 is supported by the center housing so as to be rotatable at high speed.

The intake passage 3 is constituted by internal passages of an intake pipe, an intake manifold, and an intake port.
Specifically, in the intake passage 3, an air cleaner 11 that removes dust and dirt contained in the intake air sucked into the engine 1, an intake air compressor 6 of the turbocharger 2, and intake air that has been compressed and heated by the intake air compressor 6. There are provided an intercooler 12 for forced cooling, a throttle valve 13 for adjusting the amount of intake air sucked into the engine 1, a supercharging pressure sensor 14 for detecting a supercharging pressure, etc. installed in a surge tank or the like.

The exhaust passage 4 is constituted by internal passages of an exhaust port, an exhaust manifold, and an exhaust pipe.
Specifically, in the exhaust passage 4, the exhaust turbine 5 of the turbocharger 2, the exhaust gas purifying device 15 (specifically, a catalyst or the like) that has passed through the exhaust turbine 5, the exhaust noise is silenced, and the exhaust gas is discharged into the atmosphere A muffler 16 and the like for discharging are provided.

  The turbocharger 2 is of a variable capacity type, and the turbine housing 5b bypasses the turbine impeller 5a and the flow rate adjusting valve 18 for adjusting the opening degree of the exhaust gas introduction passage 17 that guides the exhaust gas to the turbine impeller 5a. And a wastegate valve 20 for adjusting the opening degree of the bypass passage 19 that guides the exhaust gas to the exhaust downstream side of the turbine impeller 5a.

  Specifically, independent first and second exhaust scrolls 21 and 22 for turning the exhaust gas discharged from the engine 1 and blowing it to the turbine impeller 5a are provided inside the turbine housing 5b. The first and second exhaust scrolls 21 and 22 are respectively formed around the turbine impeller 5a. The first exhaust scroll 21 is provided so that exhaust gas discharged from the engine 1 always flows in. ing.

The turbine housing 5 b is provided with an exhaust gas introduction path 17 that guides the exhaust gas flowing into the turbine housing 5 b to the second exhaust scroll 22. The exhaust gas introduction path 17 is a communication hole formed in the turbine housing 5 b and is opened and closed by a flow rate adjusting valve 18.
The flow rate adjustment valve 18 adjusts the opening degree of the exhaust gas introduction passage 17, and by adjusting the opening degree of the flow rate adjustment valve 18, the exhaust gas amount from the second exhaust scroll 22 toward the turbine impeller 5 a. To control the boost pressure.

On the other hand, in the turbine housing 5b, a bypass passage 19 is formed in which a part of the exhaust gas flowing into the turbine housing 5b is bypassed to bypass the turbine impeller 5a and led to the exhaust downstream side (muffler side). .
The bypass 19 is opened and closed by a waste gate valve 20. The wastegate valve 20 adjusts the opening of the bypass passage 19, and by adjusting the opening of the wastegate valve 20, the amount of exhaust gas that bypasses the turbine impeller 5a is controlled and the boost pressure is increased. To control.

Next, with reference to FIG. 2, the drive mechanism of the flow regulating valve 18 and the wastegate valve 20 will be described.
The flow rate adjustment valve 18 and the wastegate valve 20 are driven to open and close by a single actuator 23.
Between the actuator 23 and the waste gate valve 20, a link device 24 for converting the output of the actuator 23 to drive the waste gate valve 20 is provided, and the opening degree of the flow rate adjusting valve 18 is being changed by the link device 24. As a result, the waste gate valve 20 is opened.

  The flow rate adjusting valve 18 may be directly driven by the actuator 23 without using a link mechanism, but in this embodiment, as shown in FIG. Indicates.

The actuator 23 generates rotation output or stroke output by energization control, and employs an electric actuator that generates rotation output as an example.
A specific example of the electric actuator is a combination of an electric motor (for example, a DC motor) that generates a rotational output by energization and a reduction device (for example, a gear reduction device) that increases the output torque by decelerating the rotational output of the electric motor. In other words, a rotational torque corresponding to the amount of current applied to the electric motor is generated.

The actuator 23 may include a return spring that returns the output shaft to the initial position, or may not include a return spring.
Even if the return spring is not built in the actuator 23, by providing the return spring in each of the flow rate adjustment valve 18 and the wastegate valve 20, the restoring force of each return spring is transmitted to the actuator 23 via the link device 24. Therefore, the output shaft of the actuator 23 can be returned to the initial position when the actuator 23 is stopped.
Of course, an auxiliary return spring having a small urging force may be provided in the actuator 23 to generate a force for returning the output shaft of the actuator 23 to the initial position.

The actuator 23 includes an actuator position sensor 25 that detects an output displacement.
A specific example of the actuator position sensor 25 is a rotation angle sensor that detects an operating angle (rotation angle) of the output shaft. The rotation angle sensor may be a non-contact type using a magnetic sensor or the like, or a contact type using a potentiometer or the like. The sensor output of the actuator position sensor 25 is output to the ECU 26 that controls the opening of the flow rate adjusting valve 18 and the waste gate valve 20.

The link device 24
(I) As indicated by a solid line FL in FIG. 4A, as the operating angle of the actuator 23 (specifically, the displacement angle of the output shaft) increases, the opening of the flow rate adjusting valve 18 is fully opened from the fully closed state. While gradually increasing towards the direction,
(Ii) As shown by the solid line WG in FIG. 4A, the wastegate valve 20 is opened while the operating angle of the actuator 23 is increasing, and after the opening, the wastegate is increased as the operating angle of the actuator 23 increases. The opening degree of the valve 20 is gradually increased toward the fully open direction.

  The specific structure of the link device 24 is not limited. For example, a cam link mechanism using a cam groove, a wire that controls the valve opening start position by the play amount provided on the wire and adjusts the driving torque by the pulley diameter. Various mechanisms such as a transmission mechanism that controls a valve opening start position by combining a mechanism, a lock mechanism using a spring force, and a release mechanism are applicable.

  The actuator 23 and the link device 24 are attached to the side of the intake compressor 6 that is not easily affected by the heat of the exhaust gas (which is an example and not limited), and as shown in FIG. 2, from the link device 24 to the flow rate adjustment valve 18. The output is transmitted via the first rod 27, and the output is transmitted from the link device 24 to the waste gate valve 20 via the second rod 28.

  The specific structures of the flow rate adjustment valve 18 and the wastegate valve 20 are not limited, but as an example, a hinge valve structure in which the valve body is rotated as shown in FIG. 2 is adopted.

  Specifically, the flow rate adjusting valve 18 couples the valve body that directly opens and closes the exhaust gas introduction path 17, a rotation shaft that is rotatably supported with respect to the turbine housing 5 b, and the rotation shaft and the valve body. An internal arm and an external arm that is arranged outside the turbine housing 5b and connects the rotating shaft and the end of the first rod 27 are provided, and the flow rate adjusting valve 18 is opened and closed by the stroke displacement of the first rod 27. Operated.

  The wastegate valve 20 has the same structure as the flow rate adjusting valve 18 described above, a valve body that directly opens and closes the bypass passage 19, a rotating shaft that is rotatably supported by the turbine housing 5b, An internal arm that couples the rotary shaft and the valve body, and an external arm that is disposed outside the turbine housing 5b and connects the rotary shaft and the end of the second rod 28 are provided. The waste gate valve 20 is opened and closed by the stroke displacement.

As described above, the turbocharger 2 of this embodiment is
A turbine impeller 5a for driving the compressor impeller 6a;
A flow rate adjustment valve 18 for adjusting the opening degree of the exhaust gas introduction path 17, and
A wastegate valve 20 for adjusting the opening degree of the bypass passage 19,
An actuator 23 for driving the flow rate adjusting valve 18;
A link device 24 that converts the output of the actuator 23 and opens the waste gate valve 20 in the middle of changing the opening of the flow rate adjusting valve 18 is provided.
A configuration is adopted in which the actuator 23 is energized and controlled by the ECU 26.

Next, terms used in the following will be explained collectively.
Below,
The minimum opening of the flow rate adjustment valve 18 (the fully closed opening in this embodiment) is set to the minimum adjustment valve opening θ0,
-The maximum opening of the flow rate adjusting valve 18 is set to the maximum adjusting valve opening θn,
When the flow rate adjusting valve 18 is changed from the adjusting valve minimum opening θ0 to the adjusting valve maximum opening θn, the opening range of the flow adjusting valve 18 at which the turbine correction flow rate becomes maximum becomes the saturation range θL,
The opening at which the flow rate adjustment valve 18 is minimum in the saturation range θL is the minimum saturation opening θL0,
The opening at which the wastegate valve 20 changes from closing to opening when the flow rate adjusting valve 18 is changed from the adjusting valve minimum opening θ0 to the adjusting valve maximum opening θn is referred to as a bypass start opening θα.
The turbine corrected flow rate is obtained by correcting the flow rate of the exhaust gas flowing into the turbine with the pressure of the exhaust gas and the temperature of the exhaust gas.

When the opening degree of the flow rate adjusting valve 18 is changed, as shown in FIG. 3A, the turbine corrected flow rate at the equal expansion ratio increases as the opening degree increases.
However, the relationship between the opening of the flow rate adjusting valve 18 and the turbine corrected flow rate is such that, as shown in FIG. 3B, when the opening of the flow rate adjusting valve 18 reaches the saturation minimum opening θL0, the turbine corrected flow rate becomes maximum. In the saturation range θL, even if the opening degree of the flow rate adjusting valve 18 is changed, the capacity characteristic of the turbine does not change.

Here, unlike the present invention, when the detour start opening θα at which the wastegate valve 20 starts to open is set within the saturation range θL, the broken line Pj (change in supercharging pressure) in FIG. As shown in (Characteristics), even if the actuator 23 is changed to change the opening of the flow rate adjusting valve 18, a supercharging pressure dead zone Z in which the supercharging pressure does not change occurs.
That is, the actuator operating angle ηαj at which the wastegate valve 20 starts to open (the output angle of the actuator 23 when the bypass start opening θα) is larger than the actuator operating angle ηL0 when the saturation minimum opening θL0 is reached. When set, the supercharging pressure dead zone Z is generated within the change range of the actuator 23.

Although the story goes away, the ECU 26 of this embodiment controls the actuator 23 by pressure feedback (this is an example and is not limited).
Specifically, the ECU 26 is an engine control unit in which a microcomputer is mounted, and the operating state of the engine 1 (the engine speed detected by the engine speed sensor 29 provided in the engine 1 and the throttle valve 13). The target boost pressure suitable for the operating state of the engine 1 is calculated from the opening degree and the like. The ECU 26 feedback-controls the actuator 23 so that the actual boost pressure (intake pressure) detected by the boost pressure sensor 14 matches the target boost pressure calculated by the ECU 26. The feedback control employs a well-known technique such as PID control or PI control.

Returning to the description, as described above, a failure when the target boost pressure changes in the case where the boost pressure dead zone Z exists within the change range of the actuator 23 will be described with reference to FIG.
First, as shown by the solid line X in the upper time chart of FIG. 5A, the target supercharging pressure changes.
Then, the “actuator operating angle ηαj at which the wastegate valve 20 starts to open” in the lower time chart of FIG. 5A increases, and the change width of the actuator operating angle increases as shown by the broken line J1. (A) As shown by the broken line J2 in the middle time chart, the feedback correction amount greatly fluctuates.
As a result, as shown by the broken line J3 in the upper time chart of FIG. 5A, the actual boost pressure fluctuates and the drivability deteriorates, and the actual boost pressure converges to the target boost pressure. It takes time to do. That is, the presence of the supercharging pressure dead zone Z within the change range of the actuator 23 causes deterioration of drivability and supercharging pressure controllability.

  As a means for solving the above problem, the turbocharger 2 of the first embodiment sets the “detour start opening θα at which the wastegate valve 20 starts to open in the middle of the opening change of the flow adjustment valve 18” as “the flow adjustment valve 18. Than the minimum saturation opening θL0 at which the flow rate adjustment valve 18 is minimum in the saturation range θL in which the turbine correction flow rate is maximum when the minimum adjustment valve opening θ0 is changed to the maximum adjustment valve opening θn. It is set to “adjustment valve minimum opening θ0 side” of the flow rate adjustment valve 18. That is, the detour start opening θα is set closer to the adjustment valve minimum opening θ0 than the saturation minimum opening θL0.

  This will be explained by the operating angle of the actuator 23. The actuator operating angle ηα1 (the output angle of the actuator 23 when the bypass gate opening angle θα is the opening angle) at which the wastegate valve 20 starts to open is the saturation minimum opening θL0. The actuator operating angle is set to be smaller than the current actuator operating angle ηL0.

By providing in this way, the malfunction which the supercharging pressure dead zone Z mentioned above in the change range of the actuator 23 arises can be avoided.
Specifically, the change characteristic of the supercharging pressure with respect to the operating angle of the actuator 23 is compared with the “clear staircase supercharging pressure characteristic” of the prior art as shown by a solid line P1 in FIG. It can approach “continuous boost pressure characteristics”.
The broken line Pfl in FIG. 4B indicates the boost pressure characteristic by only the flow rate adjusting valve 18, and the broken line Pwg in FIG. 4B indicates the boost pressure characteristic by only the wastegate valve 20. Is.

An operation example of the first embodiment will be described.
In the first embodiment, the supercharging pressure dead zone Z does not exist in the change range of the actuator 23 by adopting the above configuration. In this case, an operation example when the target supercharging pressure changes will be described with reference to FIG.
First, as shown by the solid line X in the upper time chart of FIG. 5A, the target supercharging pressure changes.
Then, the “actuator operating angle ηα1 at which the wastegate valve 20 starts to open” in the lower time chart of FIG. 5A is set to be smaller than the prior art (see the operating angle ηαj). Therefore, the change width of the actuator operating angle can be reduced as shown by the solid line H1, and the feedback correction amount can be reduced as shown by the solid line H2 in the middle time chart of FIG.
As a result, as shown by the solid line H3 in the upper time chart of FIG. 5A, the fluctuation of the actual supercharging pressure can be suppressed, and the time for the actual supercharging pressure to converge to the target supercharging pressure can be reduced. (Refer to the broken line J3).

(Effect of Example 1)
In the turbocharger 2 of the first embodiment, as described above, the detour start opening θα at which the wastegate valve 20 starts to open is set to the adjustment valve minimum opening θ0 side from the saturation minimum opening θL0. That is, the “actuator operating angle ηα1 at which the wastegate valve 20 starts to open” is set to “an operating angle smaller than the actuator operating angle ηL0 at the time of the minimum saturation opening θL0”.
Thereby, since the supercharging pressure dead zone Z described above can be eliminated within the change range of the actuator 23, the supercharging pressure can be continuously changed without interruption by changing the actuator 23. As a result, when the target supercharging pressure changes, fluctuations in the actual supercharging pressure can be suppressed, and the time for the actual supercharging pressure to converge to the target supercharging pressure can be shortened. That is, by adopting the present invention, it is possible to improve drivability and boost pressure controllability.

[Example 2]
A second embodiment will be described with reference to FIGS. In the following embodiments, the same reference numerals as those in the first embodiment indicate the same functions.
In the first embodiment, the technology for setting the upper limit value of the detour start opening θα at which the wastegate valve 20 starts to open (that is, the upper limit value of the actuator operating angle ηα1 at which the wastegate valve 20 starts to open) has been disclosed.
On the other hand, this embodiment shows a more preferable setting technique of the detour start opening degree θα at which the wastegate valve 20 starts to open (that is, a preferable setting technique of the actuator operating angle ηα2 at which the wastegate valve 20 starts to open). Is.

As described above, the actuator 23 includes the actuator position sensor 25 (a rotation angle sensor as a specific example) that detects an output displacement.
The control resolution of the actuator 23 by the ECU 26 is determined by the detection resolution of the actuator position sensor 25. That is, the control resolution of the actuator 23 near the detour start opening θα is the minimum control opening Δ determined by the minimum detection angle of the actuator position sensor 25.

The absolute value of the change range of the supercharging pressure sensitivity when the actuator 23 is driven from the bypass start opening θα to the maximum adjustment valve opening θn by the minimum control opening Δ is defined as a valve opening change width A.
That is, the absolute value of the change range of the supercharging pressure sensitivity when the actuator 23 is driven to the side where the operating angle is increased by the minimum control opening degree Δ from the actuator operating angle ηα2 at which the wastegate valve 20 starts to open is opened. A side change width A is assumed.

On the other hand, the absolute value of the change width of the boost pressure sensitivity when the actuator 23 is driven from the bypass start opening θα to the adjustment valve minimum opening θ0 side by the minimum control opening Δ is referred to as a valve closing side change width B.
That is, the absolute value of the change range of the supercharging pressure sensitivity when the actuator 23 is driven to the side where the operating angle is reduced by the minimum control opening degree Δ from the actuator operating angle ηα2 at which the wastegate valve 20 starts to open is closed. The side change width is B.

As the ratio of the valve opening side change width A and the valve closing side change width B is smaller, the change characteristic of the supercharging pressure with respect to the change of the actuator operating angle becomes smoother, and the supercharging pressure controllability can be improved.
Therefore, in this embodiment, a configuration is adopted in which the valve opening side variation width A is set within a predetermined value times the valve closing side variation width B. Specifically, in order to ensure the continuity of the change characteristic of the supercharging pressure, it is desirable to set the valve opening side change width A within three times the valve closing side change width B. In a more preferred embodiment, the valve opening side change width A is set within one time of the valve closing side change width B for the purpose of smoothing the change characteristic of the supercharging pressure.

Thus, by setting the valve opening side change width A to be within three times the valve closing side change width B, the change characteristic of the supercharging pressure with respect to the operating angle of the actuator 23 is shown by a solid line P2 in FIG. As shown, it can be close to “continuous and smooth supercharging pressure characteristics”.
Note that the solid line K in FIG. 6C shows the supercharging pressure sensitivity characteristic with respect to the actuator operating angle (change characteristic of the absolute value of the change amount of the supercharging pressure when the actuator 23 is changed). A broken line Kfl in FIG. 6 (c) indicates a boost pressure sensitivity characteristic by only the flow rate adjusting valve 18, and a broken line Kwg in FIG. 6 (c) indicates a boost pressure sensitivity characteristic by only the wastegate valve 20. It is.

An operation example of the second embodiment will be described.
As indicated by a solid line X in the upper time chart of FIG. 5A, the target supercharging pressure changes.
Then, “actuator operating angle ηα2 at which the wastegate valve 20 starts to open” in the lower time chart of FIG. 5A is set to be smaller than the first embodiment (see operating angle ηα1). As a result, the change range of the actuator operating angle can be reduced as indicated by the broken line I1, and the feedback correction amount can be reduced as indicated by the broken line I2 in the middle time chart of FIG.

As a result, as shown by the broken line I3 in the upper time chart of FIG. 5A, the fluctuation of the actual supercharging pressure can be further suppressed than in the first embodiment, and the actual supercharging pressure converges to the target supercharging pressure. It is possible to further shorten the time for performing the process.
That is, by adopting the second embodiment, it is possible to suppress fluctuations in the actual supercharging pressure when the target supercharging pressure changes, and to shorten the time for the actual supercharging pressure to converge to the target supercharging pressure. can do.

  In the above embodiment, the example in which the actuator 23 is controlled by pressure feedback has been described. However, the actuator 23 may be controlled by feedback of the mechanical output value of the actuator 23. As a specific example, the target operating angle of the actuator 23 is calculated from the target boost pressure, and the ECU 26 feedback-controls the actuator 23 so that the actual operating angle detected by the actuator position sensor 25 matches the target operating angle. May be.

  In the above embodiment, the example in which the actuator 23 is feedback-controlled has been shown, but the actuator 23 may be feedforward controlled (open control). As a specific example, the target operating angle of the actuator 23 is calculated from the target boost pressure, the target energization amount corresponding to the target operating angle is calculated, and the electric power corresponding to the target energization amount is applied to the electric motor. good.

5a Turbine impeller 6a Compressor impeller 17 Exhaust gas introduction path 18 Flow rate adjustment valve 19 Bypass path 20 Wastegate valve 23 Actuator 24 Link device

Claims (5)

A turbine impeller (5a) for driving a compressor impeller (6a) for intake air compression;
A flow rate adjusting valve (18) for adjusting the opening degree of the exhaust gas introduction passage (17) for introducing the exhaust gas to the turbine impeller (5a);
A wastegate valve (20) that adjusts the opening of a bypass passage (19) that bypasses the turbine impeller (5a) and guides exhaust gas to the exhaust downstream side;
An energizable controllable actuator (23) for driving the flow rate adjusting valve (18) directly or indirectly;
A link for converting the output of the actuator (23) to drive the wastegate valve (20) and opening the wastegate valve (20) in the middle of changing the opening of the flow rate adjusting valve (18). A device (24);
In the turbocharger (2) having
The minimum opening of the flow rate adjusting valve (18) is set as the adjusting valve minimum opening θ0,
The maximum opening degree of the flow rate adjusting valve (18) is set as the adjusting valve maximum opening degree θn,
When the flow rate adjustment valve (18) is changed from the adjustment valve minimum opening degree θ0 to the adjustment valve maximum opening degree θn, the opening range of the flow rate adjustment valve (18) at which the turbine correction flow rate becomes maximum is set to a saturation range θL,
Within this saturation range θL, the opening at which the flow rate adjusting valve (18) is minimized is the saturation minimum opening θL0,
When the flow rate adjusting valve (18) is changed from the adjusting valve minimum opening θ0 to the adjusting valve maximum opening θn, the opening at which the wastegate valve (20) changes from closing to opening is bypassed. If θα,
The turbocharger (2), wherein the detour start opening θα is set to the adjustment valve minimum opening θ0 side with respect to the saturation minimum opening θL0. The turbocharger (2) according to claim 1,
The control resolution of the actuator (23) at the detour start opening θα is set to the minimum control opening Δ,
The absolute value of the change width of the boost pressure sensitivity when the actuator (23) is driven by the minimum control opening degree Δ from the detour start opening degree θα to the adjustment valve maximum opening degree θn side is defined as a valve opening side change width A,
The absolute value of the change width of the supercharging pressure sensitivity when the actuator (23) is driven to the adjustment valve minimum opening degree θ0 side by the minimum control opening degree Δ from the detour start opening degree θα is the valve closing side change width B. if you did this,
The turbocharger (2), wherein the valve opening side change width A is set within a predetermined value times the valve closing side change width B. The turbocharger (2) according to claim 2,
The turbocharger (2), wherein the valve opening side change width A is set within three times the valve closing side change width B. In the turbocharger (2) according to claim 2 or claim 3,
The actuator (23) includes an actuator position sensor (25) for detecting an output displacement of the actuator (23).
The turbocharger (2), wherein the control resolution of the actuator (23) is a detection resolution of the actuator position sensor (25). In the turbocharger (2) according to any one of claims 1 to 4,
This turbocharger (2) is a turbine housing having independent first and second exhaust scrolls (21, 22) that swirl exhaust gas discharged from the engine (1) and spray it onto the turbine impeller (5a). 5b)
The turbocharger (2), wherein the exhaust gas introduction path (17) whose opening degree is adjusted by the flow rate adjusting valve (18) is a communication hole for introducing exhaust gas to the second exhaust scroll (22). .

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